1. Field of the Invention
The present invention relates generally to telecommunications networks, and more particularly to the shaping of round trip time delay network packet transmission characteristics to reduce the number of packet time outs occurring during established sessions.
2. Description of Related Art
In conventional telecommunications or data communications networks, communicating nodes establish end-to-end sessions utilizing protocols such as TCP. When a source node transmits a packet to a destination node, it also sets a timer to open an acknowledgement period, based on a TCP-specific algorithm for packet traffic characteristics, during which the destination node must acknowledge correct receipt of the packet. If the source node does not receive an acknowledgement from the destination node before the timer expires, the timer issues a time out, the packet is determined to be lost, and the source node must retransmit the packet to the destination node.
For transmission of TCP packets over a wireless network such as a code division multiple access cdma2000 network, packets exchanged during a TCP session may be transmitted over different physical channels over the wireless link. Packets transmitted over these channels may experience widely varying delays. In the case of a cdma2000 network, the transmission time delay characteristics of the two physical channels available may be an order of magnitude apart (typically tens of milliseconds versus hundreds of milliseconds). Generally, longer packets may be transmitted over the slower channel, while shorter packets, such as packets containing only acknowledgements, may be transmitted over the faster channel, which is the channel that has a smaller capacity per frame. As the above-mentioned TCP-specific algorithm bases the timer acknowledgement period on packet traffic characteristics, if a string of shorter packets is transmitted over the second channel, the time out value generated by the TCP-specific algorithm will be progressively reduced to the point that the transmission of one longer packet on the first channel will cause a time out and therefore cause the longer packet to be re-transmitted. In addition to re-transmitting the packet, the source node may also erroneously determine that the time out was due to network congestion and therefore may reduce the rate of transmission of outgoing packets, thereby further reducing throughput and causing inefficient utilization of the wireless network.